Methods and apparatus for broadcasting data

ABSTRACT

A broadband data broadcast system that allows rich multimedia content to be delivered to a plurality of subscribers is disclosed. The broadband data broadcast system operates by multiplexing a plurality of rich multimedia digital information streams together at a centralized data broadcast center. The data broadcast center then broadcasts the multiplexed digital information stream on a broadcast medium such as satellite broadcasts, radio frequency broadcasts, or digital television broadcasts. A large number of receiver systems receive the broadcast signal and demodulate the broadcast signal to retrieve the multiplexed digital stream. The receiver system extracts a subset of digital information streams that the particular receiver system&#39;s owner has designated are of interest. The receiver system caches the interesting digital information stream for later access. The receiver system outputs the interesting digital information streams to a client system upon demand. The receiver system may also stream an incoming digital information stream to a client as the stream is received.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/560,674, filed Apr. 27, 2000 now abandoned, which is a divisional ofU.S. patent application Ser. No. 09/293,594, filed Apr. 16, 1999 nowU.S. Pat. No. 6,526,580.

FIELD OF THE INVENTION

The present invention relates to the field of digital communications. Inparticular the present invention discloses a broadband digital broadcastsystem for broadcasting digital information to a very large number ofsubscribers.

BACKGROUND OF THE INVENTION

The Internet has become a major source of news and information for verylarge numbers of people. In particular, millions of Internet usersbrowse the World Wide Web (WWW) to obtain HyperText Markup Language(HTML) documents using the HyperText Transport Protocol (HTTP). Manypeople now receive more news and information from the Internet WWW sitesthan from traditional information sources such as television. The WWWportion of the Internet is an excellent medium for news and informationsince the WWW Internet sites can provide information to users on-demand.Specifically, Internet users can immediately request the exactinformation they are interested in when ever they wish from WWW Internetsites.

However, the Internet WWW system news information does suffer from anumber of deficiencies. One serious problem is that the limitedbandwidth of most Internet connections severely limits the amount ofinformation delivered. Most Internet users access the Internet through adial-up modem at speeds of 56 kps per second or less. With such limitedbandwidth, most Internet based WWW sites only deliver text and staticimages. When video information delivered through 56 K Internetconnections the video information is compressed so heavily such thatonly small low-resolution video images are delivered at a low framerate.

To improve upon the performance of the Internet, many telecommunicationproviders are now offering high-bandwidth connections for the “lastmile” to an Internet user's residence. Cable television providers arenow offering cable modem Internet service that use cable televisionwiring to deliver broadband Internet service. Similarly, telephonecompanies are rolling out Digital Subscriber Line (DSL) services thatprovide broadband Internet service. Although these broadband dataconnections provide additional bandwidth, such broadband connectionsonly address the “last mile” bandwidth problem associated with sendingrich multi-media information across the Internet. Many other problemswill continue to exist.

One problem of delivering rich multi-media information across theInternet is that there are no standard quality-of-service guarantees forInternet Protocol data traffic. All Internet Protocol traffic isdelivered on a best effort basis such that Internet Protocol packets areoften dropped. Due the rapid uncontrolled growth of the Internet, manysevere Internet “traffic jams” have occurred at large Internet peeringpoint such as MAE-East and MAE-west. Thus, even if a user has abroadband connection between his residence and his Internet ServiceProvider (ISP), there is no guarantee that the connection between theInternet Service Provider (ISP) and a desired Internet media server willprovide the bandwidth necessary for a rich multimedia stream.

Another problem with attempting to deliver rich multi-media informationacross the Internet is the point-to-point nature of Internetcommunication. Most Internet communication occurs in a unicast mannerwherein a unique communication connection is established between eachinformation server and each Internet client. Since each Internet clientrequires its own connection, the bandwidth requirement for servinginformation grows linearly with the number of Internet clients beingserved. Furthermore, each Internet client that requests service addsadditional load to the server systems that service information. To serverich multimedia information to a large number of a client systems, alarge powerful server farm is required. It is therefore quite expensivefrom the server end in both communication costs and computer costs toserve large amounts of rich multi-media information.

Due to the above-described problems associated with Internet delivery ofmultimedia information, the Internet will largely remain a text andstatic image based information source. It would be desirable to providea multi-media rich information system that is similar to the Internet interms of on-demand access of interesting information but without thebandwidth problems associated with the Internet network system.

SUMMARY OF THE INVENTION

The present invention discloses a broadband data broadcast system thatallows rich multimedia content to be delivered to the computer andinformation appliance systems of limitless numbers of subscribers. Thebroadband data broadcast system operates by multiplexing a plurality ofmultimedia rich digital information streams together at a centralizeddata broadcast center. The data broadcast center then broadcasts themultiplexed digital information stream on a broadcast medium such assatellite broadcasts, radio frequency broadcasts, or televisionbroadcasts. A large number of receiver systems receive the broadcastsignal and demodulate the broadcast signal to retrieve the multiplexeddigital stream. The receiver system extracts a subset of digitalinformation streams that the particular receiver system's owner hasdesignated are of interest. The receiver system then output theinteresting digital information streams to a display system or cachesthe interesting digital information stream for later access.

Other objects, features, and advantages of present invention will beapparent from the company drawings and from the following detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, features, and advantages of the present invention will beapparent to one skilled in the art, in view of the following detaileddescription in which:

FIG. 1 illustrates an overview of a terrestrial data broadcast system.

FIG. 2 a illustrates an overview of a multiple broadcaster basedterrestrial data broadcast system.

FIG. 2 b illustrates a block diagram of a multiple broadcaster basedterrestrial data broadcast system.

FIG. 3 a illustrates a multimedia receiver/server system coupled to apersonal computer system.

FIG. 3 b illustrates a multimedia receiver/server system coupled to atelevision set-top box system.

FIG. 3 c illustrates a multimedia receiver/server system coupled to apersonal computer system that is also coupled to the Internet.

FIG. 3 d illustrates a multimedia receiver/server system coupled to atelevision set-top box system that is also coupled to the Internet.

FIG. 4 illustrates an embodiment of a multimedia receiver/server systemcoupled to a computer network such that the multimedia receiver/serversystem serves multiple client systems.

FIG. 5 illustrates an embodiment of a multimedia receiver/server systemthat receives a data broadcast from a direct video broadcast satellite.

FIG. 6 a illustrates an embodiment of a multimedia receiver/serversystem that receives a data broadcast on a digital televisionbroadcaster signal.

FIG. 6 b illustrates a block diagram of a multimedia receiver/serversystem that receives data broadcasts from multiple digital televisionbroadcasters.

FIG. 7 illustrates a conceptual flow diagram of one possible softwarearchitecture for a multimedia receiver/server system.

FIG. 8 illustrates a first possible screen display from a multimedia webpage served by a multimedia receiver/server system.

FIG. 9 illustrates a conceptual diagram of hierarchical multimediainformation pages generated and stored by a multimedia receiver/serversystem.

FIG. 10 illustrates a second possible screen display generated by andserved from a multimedia web page served by a multimedia receiver/serversystem.

FIG. 11 illustrates a third possible screen display generated by andserved from a multimedia web page served by a multimedia receiver/serversystem.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A method and apparatus for a directed data broadcast system isdisclosed. In the following description, for purposes of explanation,specific nomenclature is set forth to provide a thorough understandingof the present invention. However, it will be apparent to one skilled inthe art that these specific details are not required in order topractice the present invention. For example, the present invention hasbeen described with reference to Internet multicasting. However, thesame techniques can easily be applied to other types of datacommunication protocols.

Overview of a Data Broadcast System

FIG. 1 illustrates an overview of one embodiment of a data broadcastsystem that may incorporate the teachings of the present invention.Referring to FIG. 1, a data broadcast control center 150 receivesdigital information from a number of different data origination sources110, 113, and 115.

For example, a first data origination source 110 transmits a digitalinformation stream to a data broadcast facility 150 along a datacommunication channel 130. The data origination source 110 may be anyentity that provides digital information for broadcast data over a databroadcast medium. One type of entity that may provide digitalinformation for broadcast data over a data broadcast medium may be abroadcast news studio that creates audio and/or video news segments. Theaudio and/or video news segments may be digitized before or aftertransmission to the broadcast facility 150

The broadcast control center 150 processes the incoming digitalinformation stream from data origination source 110 by adding addressinginformation, stream descriptor information, and error correction coding.Other stream processing operations may be performed such as encryptionof the information streams. The broadcast control center 150 thenmultiplexes the received digital information stream from dataorigination source 110 with digital information streams from othersources such as data origination source 113 and data origination source115.

After processing the individual digital information streams andmultiplexing the individual digital information streams into a singlebroadcast stream, the broadcast facility 150 then modulates themultiplexed digital information stream onto a digital broadcast signal.The broadcast control center 150 then transmits the digital broadcastsignal on a broadcast distribution medium. In the particular embodimentillustrated in FIG. 1, a terrestrial wireless broadcast system is usedto broadcast the digital broadcast signal to a large number of receivingsites. However, it should noted that many types of broadcast media canbe used such as digital broadcast television signals, cable televisionsignals, radio frequency broadcasts, direct video broadcast satellitesignals, or any other suitable broadcast medium.

At each data broadcast receiver site is a data broadcast receiver systemsuch as receiver 181 constructed to receive the digital broadcastsignal. The receiver system 181 demodulates the digital broadcast signalto retrieve the multiplexed digital information stream. The receiversystem 181 then examines the address portion of data packets and/orstream descriptor portions of each digital information stream todetermine if the receiver system 181 is interested in a particulardigital information stream. The receiver system 181 may be interested ina particular digital information stream if that digital informationstream matches a set of preprogrammed interest parameters as defined bythe receiver systems owner. The receiver system 181 may cache thematching digital information streams and/or directly output the matchingdigital information streams to one or more local client systems at thereceiver system's site.

In one embodiment, the receiver system may distribute the output digitalinformation streams in multicast Internet Protocol (IP) form on a localarea network (LAN) if requested by any multicast subscribers on the LAN.For example, receiver system 184 receives and decodes the multiplexedbroadcast signal. The receiver system 184 then rebroadcasts a subset ofthe received data onto an internal local area network (LAN) 130 suchthat the information stream is made available to client systems 131,132, and 133. Furthermore, the receiver system 184 may cache thereceived digital information internally such that the information may beretrieved by the client systems at a later time.

Terrestrial Digital Television Data Broadcast Distribution

One broadcast medium that may be used to broadcast digital informationis the terrestrial digital television infrastructure that is currentlybeing built out. In a terrestrial digital television based transmissionsystem, the processed multiplexed information stream is broadcast on adigital television transmission system using the MPEG-2 transportprotocol.

The cost of building and maintaining a terrestrial digital televisiontransmission system is very high. It would therefore be very expensiveto build a terrestrial digital television transmission system just fordata broadcasting. Instead, it would be desirable to share terrestrialdigital television broadcast transmission capability with a terrestrialdigital television broadcaster. Thus, the present invention introducesan embodiment that uses extra broadcast capacity on terrestrial digitaltelevision transmission systems to provide an inexpensive data broadcasttransmission system. In a preferred embodiment, extra digital broadcasttransmission capacity from more than one digital television broadcastermay be used to provide broadband data broadcasting.

FIG. 2 a illustrates a data broadcasting embodiment wherein the databroadcast control center 150 delivers MPEG-2 transport protocol encodedinformation streams to one or more terrestrial digital televisionbroadcast centers 251, 252, and 253. The terrestrial digital televisionbroadcast centers (251, 252, and 253) merge the received MPEG-2transport protocol encoded information streams into their ATSC (AdvancedTelevision Standards Committee) digital television signals. Theterrestrial digital television broadcast centers 251, 252, and 253 thenbroadcast the merged signal to all the receiver systems through theirdigital television transmission systems 261, 262, and 263. The receiversystems (181, 182, 183 . . . ) receive the ATSC digital televisionsignals and extract the desired digital information streams from theMPEG-2 transport stream. In such a multi-broadcaster embodiment, eachreceiver system (181, 182, 183 . . . ) should have more than onereceiver circuit such that multiple digital television broadcast centers(251, 252, and 253) can be monitored simultaneously.

FIGS. 2 a and 2 b illustrate a block diagram of the embodiment inFIG. 1. As illustrated in the block diagrams of FIGS. 2 a and 2 b, amultiplexing unit 257 must multiplex all of the processed digitalinformation streams into a number of outgoing digital informationstreams equal to the number of broadcast stations being used. Forexample, in the example embodiment of FIGS. 2 a and 2 b, themultiplexing unit 257 must distribute the outgoing digital informationstream to the three digital television broadcast stations 251, 252, and253.

The individual digital television broadcast stations 251, 252, and 253multiplex the data broadcast information in with their local digitaltelevision signal. The individual digital television broadcast stations251, 252, and 253 may also multiplex in additional locally generateddata broadcast content. For example, digital television broadcaststations 251 may create additional data broadcast formatted content withlocal advertisers and local news teams. These local content digitalinformation streams provide additional data broadcast content to thedata broadcast digital information streams. All of the receiver systems(181, 182, 183 . . . ) will receive the data broadcast signals from allthe participating television broadcaster stations (251, 252, and 253).

Additional detailed information on a data broadcasting infrastructurethat can use the teachings of the present invention is available in theco-pending patent application entitled “Method and Apparatus forBroadcasting Data With Access Control” having Ser. No. 09/293,079, filedconcurrently with this patent application and hereby incorporated byreference.

Data Broadcast Receiver Systems

The receiver systems of the present invention receive data broadcastinformation and present that information to users of the receiversystem. In one embodiment, the data broadcast receiver systems receivethe data broadcast streams and present that information to other clientsystems that display the received digital information. Such anembodiment is referred to as a wireless multimedia receiver/serverdevice since multimedia information is received over a wireless mediumand served to other client systems.

FIG. 3 a illustrates a first example usage of a wireless multimediareceiver/server device. In the embodiment of FIG. 3 a, a personalcomputer system 310 is coupled directly to a wireless multimediareceiver/server device 330. A number of different interface ports oncomputer system 310 may be used for such a connection. For example, aparallel data port, a Small Computer System Interface (SCSI), anEthernet interface (using a cross-over cable), a FireWire™ Bus(IEEE.1394), or a Universal Serial Bus (USB) interface may be used tocouple computer system 310 to wireless multimedia receiver/server device330. It is desirable to select the available computer interface havingthe highest data rate in order to efficiently deliver rich multimediacontent from the multimedia receiver/server device 330 to the computersystem 310.

The wireless multimedia receiver/server device is not limited to usageby personal computer systems. FIG. 3 b illustrates an example usagewherein a television set-top box 320 is coupled to a wireless multimediareceiver/server device 330. The television set-top box 320 may operateusing standard Internet data communication protocols such as HyperTextTransport Protocol (HTTP).

The wireless multimedia receiver/server device 330 may be used alone asillustrated in FIGS. 3 a and 3 b or in conjunction with a wired networkconnection. FIGS. 3 c and 3 d illustrate an application of a wirelessmultimedia receiver/server device 330 wherein the wireless multimediareceiver/server device 330 acts as an intermediary for an Internetconnection. In such an embodiment, the wireless multimediareceiver/server device 330 may act as a proxy server for the Internet.In such an arrangement, the wireless multimedia receiver/server device330 may provide many additional services such as local domain nameservice (DNS), web page caching, and email service. In a web pagecaching wireless multimedia receiver/server device 330, the broadcastcontrol center may broadcast versions of very popular web pages to thewireless multimedia receiver/server devices such that very popular webpages are immediately available.

The receiver systems can be used to provide service to multiple clientsystems at a receiver site. FIG. 4 illustrates a wireless multimediareceiver/server device 480 is coupled to a local area network (LAN) 450.The local area network (LAN) 450 may be constructed using standardEthernet technology, Token Ring technology, Homerun™ home LANtechnology, or any other existing or newly created computer networktechnology. In a computer network based embodiment, the wirelessmultimedia receiver/server device 480 may serve several client systemscoupled to the local area network (LAN) 450. For example, in FIG. 4 themultimedia receiver/server device 480 may serve multimedia informationto client computer systems 462, 464, 466, and 468.

Data Broadcast Receiver/Server Hardware

FIG. 5 illustrates one embodiment of a multimedia receiver/server device500. The multimedia receiver/server device 500 receives an encoded datastream through a receiver front-end receiver system 510. The receiverfront-end system 510 includes a signal reception system 505 forreceiving a digital broadcast signal and accompanying receiver circuitryfor demodulating digital broadcast signal received on the signalreception system 505. The signal reception system 505 may be a Ku bandsatellite antenna, a terrestrial broadcast digital television antenna, aconnection to a cable television based digital signal distributionsystem, or any other appropriate system for receiving broadcast signals.

A Digital Video Broadcast Satellite Based Receiver Front-End

The multimedia receiver/server device 500 of FIG. 5 illustrates asatellite based digital video broadcast based receiver front-end system510. In the digital video Broadcast based receiver front-end system 510,the signal reception system 505 may comprises a Ku Band satelliteantenna system.

The Ku Band satellite signal reception system 505 includes a low-noiseblock converter (LNB) 507 that delivers a frequency converted signal anappropriate satellite band receiver circuitry 511. The satellitereceiver circuitry 511 filters and amplifies the frequency range of thedesired satellite signal. The satellite receiver circuitry 511multiplies the filtered signal using a local oscillator to recover anin-phase (I) and quadrature (Q) version of the broadcast signal.

The satellite receiver circuitry 511 passes the in-phase (I) andquadrature (Q) signals to an analog to digital (A/D) converter 515. Theanalog to digital (A/D) converter 515 digitizes the in-phase (I) andquadrature (Q) signals and passes the digitized signal information totransport decoder circuitry 517.

The transport decoder circuitry 517 recovers the transmitted digital bitstream from the digitized in-phase (I) and quadrature (Q) signals. Inone Ku band direct video broadcast satellite embodiment, the transportdecoder circuitry 517 may includes a demodulator integrated circuit suchas the OTI-8511 integrated circuit from Oak Technology of Sunnyvale,Calif. In such a DVB satellite based system, the OTI-8511 integratedcircuit demodulates the in-phase (I) and quadrature (Q) signals torecover an MPEG-2 transport stream. The MPEG-2 transport stream isdefined by the ISO standard defined in the document ISO/EEC 138181titled “Information technology—Generic coding of moving pictures andassociated audio information: Systems.” Control circuitry in thetransport decoder circuitry 517 may copy the MPEG-2 transport streaminto an I/O memory system 520.

A Terrestrial Digital Television Based Receiver Front-End

FIG. 6 a illustrates a multimedia receiver/server device 600 that has adifferent receiver front-end receiver system. Specifically, FIG. 6 aillustrates a multimedia receiver/server device 600 with a terrestrialdigital television based receiver front-end system 610. In particular, aterrestrial digital television based upon the American TelevisionStandards Committee (ATSC) is illustrated. In the ATSC digitaltelevision based receiver front-end system 610, the signal receptionsystem 605 comprises an antenna system suitable for receiving ATSCdigital television signals.

The ATSC digital television signals are then processed by an ATSCdigital television receiver circuit 611. As in the satellite embodimentof FIG. 5, the receiver circuit 611 is used to recover an MPEG-2transport stream. The MPEG-2 transport stream is then decoded bytransport decoder circuitry 617. Since the same transport coding is usedas disclosed in the preceding receiver system, the same MPEG-2 transportstream decoder may be used to decode the signal to retrieve the MPEG-2transport stream. The output MPEG-2 transport-stream may then be placedinto the I/O memory system 520.

As noted in the embodiments of FIG. 5 and FIG. 6 a, multiple differenttypes of receiver systems can be constructed that used differentfront-end receiver systems. In this manner, slightly modified receiversystems can be built for each target market in order to take advantageof the best broadcast medium for that market. Specifically, ATSCterrestrial digital television front-end receiver systems, direct videobroadcast satellite front-end receiver systems, and digital cabletelevision front-end receiver systems can be built for ATSC terrestrialdigital television markets, direct video broadcast markets, and digitalcable television markets, respectively. With those three different typesreceiver systems, the same MPEG-2 transport systems is always used suchthat the same MPEG-2 transport signal can be used for all the differenttypes of markets.

A Multiple Tuner Terrestrial Digital Television Receiver Front-End

As illustrated in FIG. 2 a, it may be desirable to aggregate the extrabroadcast bandwidth available from a number of digital televisionbroadcasters within a particular terrestrial broadcast televisionmarket. With such an arrangement as depicted in FIG. 2 a, the receiversystems should be able to receive all of the broadcast data signals.FIG. 6 b illustrates a multimedia receiver/server device 600 thatincludes multiple instances of the receiver front-end receiver system.Specifically, FIG. 6 b illustrates a multimedia receiver/server device600 with multiple instances of the receiver circuitry 611, the Analog toDigital circuitry 615, and the transport decoder circuitry 617. In thismanner, multiple data broadcasts from multiple digital televisionbroadcasters (251, 252, and 253) can be simultaneously received. Withsuch a multiple receiver configuration, the aggregated bandwidth mayexceed multiple megabytes per second.

Receiver System Digital Information Stream Processing

Referring back to FIG. 5, once the multiplexed digital stream is copiedinto the I/O memory system 520, the processor 540 of the receiver/server500 performs additional processing of the digital stream. The processor540 is part of a typical computer system arrangement that includesmemory (memory 570 and I/O memory 520), long term storage 550,input/output devices (590, 541, 543, etc.), and a central processingunit (processor 540).

The processor 540 operates under the control of programs in the mainmemory 570. To share the computing resources of the digital receiversystem 500, the processor 540 executes an operating system 571. Theoperating system 571 provides standard operating system features such asinput/output abstraction, multitask scheduling, and memory management.The operating system allows the application software to easily accessand use the resources of the computer system. In one embodiment of thepresent invention, the operation system 571 comprises a version of theBerkeley Standard Distribution (BSD) of the UNIX operating system.However, other operation systems can be used.

Data Broadcast Receiver/Server Software

As illustrated in FIG. 5, the multimedia receiver/server 500 may executeseveral application programs concurrently under the control of anoperating system 571 to provide data broadcasting services to a user.The software of one embodiment of a multimedia receiver/server systemwill be disclosed with reference to FIGS. 5 and 7. However, manydifferent multimedia receiver/server software architectures may becreated.

Referring to FIG. 7, a conceptual software architecture diagram of amultimedia receiver/server 700 is illustrated. The software architecturehas been designed to process data broadcast information received througha receiver system 701 and present that data broadcast information to auser at a client system 799. A first step that is performed is parsingof the incoming digital information stream.

Packet Extraction and Processing

Referring the conceptual diagram of FIG. 7, a packet extraction andprocessing system 710 examines the multiplexed digital informationstream received by the receiver system 701. The packet extraction andprocessing system 710 extracts network packets that may be of interestto the multimedia receiver/server system 700. Specifically, the packetprocessing system 710 identifies and extracts packets that arespecifically addressed to the multimedia receiver/server system 700 andpackets that have specific defined characteristics. In a preferredembodiment, the data packets are Internet Protocol (IP) packets.

Referring back to FIG. 5, the packet processing is performed by one ormore decoding, filtering, and decrypting applications 572. In oneembodiment, these applications extract IP packets from MPEG-2 transportframes. The IP packet extraction may include such steps as forward errorcorrection, decryption, and packet reassembly. Normally, not all of thepackets in the multiplexed digital information stream will be extractedsince many packets may be encrypted in a manner that cannot be decryptedby this unit, addressed to other entities, or otherwise inappropriate.

Packet Routing

Referring again to FIG. 7, the extracted packets are passed to a packetrouting system 730. The packet routing system 730 routes the receivedpackets appropriate destinations. For example, certain system updatepackets may be addressed for delivery to a receiver/server updateapplication 765. The receiver/server update application 765 may therebyreceive information that allows automatic software updates to beperformed on the multimedia receiver/server system 700. Packets may alsobe routed to a management application 741 that manages the operation ofthe multimedia receiver/server system 700. For example, encryption keysthat may be used to decrypt certain digital information streams may bedelivered to the management application 741 such that the managementapplication 741 may receive encryption keys and other controlparameters.

The packet routing system 730 may route other data packets to one ormore client systems coupled to the multimedia receiver/server system 700through computer interface 790. Thus, it can be seen from FIG. 7 thatthe multimedia receiver/server system 700 may forward data packetsreceived from the data broadcast signal directly to client systemscoupled to the multimedia receiver/server system 700. In suchoperations, the multimedia receiver/server system 700 acts as a packetrouter to deliver packets broadcast over a broadcast medium. One veryuseful application for this particular feature is using the multimediareceiver/server system 700 as a multicast router that can delivermulticast packets to any client or network coupled to the multimediareceiver/server system 700. For example, a stock ticker stream may bebroadcast as a live multicast IP stream such that a stock tradingapplication on client system 799 may directly receive and use real-timestock trading information.

Referring to FIG. 5, the packet routing may be performed by a packetrouting application 577. The routing application uses the servicesprovided by the operating system 571 and device drivers 578 to deliverpackets to the proper destinations.

Information Caching

As seen in the preceding section, the multimedia receiver/server system700 can be used to immediately route packets received from the databroadcast signal. However, the multimedia receiver/server system 700 canalso be used to provide very useful data services by locally cachinginformation. Referring to FIG. 7, one or more caching applications 745(data caching application 573 in FIG. 5) receives data packets from thepacket routing system 730 and caches information from those packets intoa file system 750.

In one embodiment, the caching application 745 may request to receivepackets addressed to one or more designated multicast addresses thatcarries multimedia information and accompanying descriptors. The cachingapplication 745 selectively captures multimedia information and storesthat multimedia content information 753 in a file system 750. Thecaching application 745 may create multimedia information directory 755such that the cached multimedia information may be quickly searched andaccessed. The multimedia information may consist of anything that can beexpressed in digital form including audio, video, text, web pages, andcomputer programs.

In one embodiment, each multimedia information stream is preceded by amultimedia descriptor. The multimedia descriptor describes the detailsof the upcoming multimedia stream. The caching application 745 can usethe multimedia descriptor to determine if the upcoming multimedia streamshould be cached or not. For example, in one embodiment the user definesa set of categories that the user finds interesting. These categoriesare stored in users preferences file 757. Then, the caching application745 uses the multimedia descriptor information in conjunction with theset of user preferences 757 to select multimedia streams that containnews or information related to the defined set of user interests. Thecaching application 745 can use the multimedia descriptor to help buildthe multimedia directory 755.

The following list provides some of the information that may be providedin a multimedia descriptor:

-   -   Title: A title for the multimedia stream    -   Full Headline: A news headline that can be used to describe the        multimedia stream in a web page.    -   Origination date/time: The time the stream was broadcast.    -   Suggested expiration: A suggested expiration time for the        stream. A multimedia receiver/server may use the expiration time        to determine when the stream should be deleted from the        multimedia content cache 753.    -   Source: A source of the multimedia stream (Reuters, CNN,        Associated Press, United Press International, etc.)    -   Multimedia Stream Format: Information that describes the        protocol and format of the multimedia information stream.    -   Accompanying multimedia stream(s): Other related multimedia        streams.    -   SDP descriptor: A session description protocol (SDP) as defined        by the IETF RFC 2327 for the multimedia stream.    -   Importance: A relative importance value assigned to the        multimedia stream. The Importance value may be used when created        user displays such that highly important stories are listed        first.    -   Categorization code: A detailed categorization value that        defines the subject matter of the multimedia stream. The        categorization code may be hierarchical. For example, a        multimedia video clip about the Minnesota Vikings winning the        Superbowl may be categorized as Sports/NFL/MN_Vikings    -   Ticker Symbols: If the multimedia story is related to one or        more publicly traded corporations, the ticker symbols of those        corporations should be listed here. This field can be used to        identify stories about a public corporation when performing        investment research.    -   Searching keywords: A set of keywords that are associated with        the multimedia stream. The searching keywords can be used to        locate relevant multimedia streams when searching the multimedia        content.    -   News Item HTML: A preformatted web page that can be used to        introduce or accompany a multimedia stream.    -   News Item Text: Text that describes the multimedia stream.

As can be seen from the multimedia descriptor description, the cachingapplication 745 is provided with a large number of fields that can beused to select interesting multimedia streams. Additional fields may beused to provide additional information about the multimedia streams.

The caching application 745 may also handle cache clean up.Specifically, old and outdated information should be removed from thefile system 750 to conserve resources. The caching application 745 mayuse a number of different methods of selecting information to remove.One simple method of performing cache clean up is to remove cached itemsafter their suggested expiration time has elapsed.

Information Serving

The multimedia receiver/server system 700 may present the cachedmultimedia information in a number of different ways. However, one ofthe most popular current methods of presenting information is in theform of World Wide Web (WWW) pages formatted in HyperText MarkupLanguage (HTML) or eXtensible Markup Language (XML). One embodiment ofthe multimedia receiver/server system 700 uses a web page constructingapplication 760 to create WWW pages 759 that may be presented to clientsystems. (The web page constructing application is listed as web pagebuilding applications 576 in FIG. 5.)

The web page constructing application 760 may continually examine thecontents of the multimedia directory 755 and the multimedia content 753to locate information to be incorporated into web pages. In oneembodiment, the caching application 745 directly informs the web pageconstructing application 760 about the multimedia streams that will becached. In this manner, the web page constructing application 760 canincorporate the newly cached information into the web pages.Furthermore, the web page constructing application 760 can incorporate“live” information that is currently being received by referring to amulticast stream that contains the live stream. Similarly, the cachingapplication 745 should inform the web page constructing application 760about multimedia information being removed from the file system 750 suchthat the web page constructing application 760 can remove references todeleted information.

The web page constructing application 760 should create web pages inaccordance with the user's particular preferences. Specifically, the webpage constructing application 760 refers to the user preferences file757 to create a custom multimedia enhanced web page that specificallycontains information according to the user's preferences. In a multipleclient environment, the web page constructing application 760 may createa different customized web page for each user that uses the multimediareceiver/server system 700.

A web server application 781 serves the created web pages 759 to clientsystems that request the web pages 759. (The web server application islisted as main server application 574 on FIG. 5.) Due to the caching ofrich multimedia information, the web server 781 may be aided by one ormore file streaming applications 782 and 783. The file streamingapplications 782 and 783 stream rich multimedia information such asvideos and audio that may be incorporated into the customized web pages759. Furthermore, the web pages may incorporate “live” streaminginformation that is delivered straight from the packet routing system730. In this manner, video from live events can be incorporated directlyinto web pages.

Other methods of serving information besides using the World Wide Webprotocols and formats may also be provided. For example, server 787 mayprovide raw file information to client systems the well-known NetworkFile System (NFS). Server 787 could also be a File Transport Protocol(FTP) server. Other server applications that implement other protocolscan also be implemented.

A Data Broadcast News Application

To illustrate one type of service that may be provided by the databroadcast system of the present invention, an example of a databroadcast news application is disclosed. Referring to FIG. 7, a user ata client system creates a set of preferences that describe the user'sinterests. The user preferences may be obtained by presenting a set offorms to the user with web server 781. The forms can be processed byCommon Gateway Interface (CGI) scripts that store the user's preferencesinto user preferences file 757. For example, a user may specify that heis interested in top news stories, sports information, financialinformation, and science & technology information.

Using the user interests in the user preferences file 757, the datacaching application 745 begins collecting multimedia streams andmultimedia descriptors broadcast over the data broadcast system. Thecaching application 745 creates a multimedia directory 755 usingmultimedia descriptor information. The caching application 745 maydirectly inform the web page constructing application 760 about theinformation streams that are being cached.

The web page constructing application 760 then uses the user preferenceinformation 757 along with multimedia descriptor information from thecaching application 745 or from the multimedia directory 755 to create acustomized multimedia enhanced web page for the user. FIG. 8 illustratesone possible example of a customized new web page created for theexample user that is interested in top news stories, sports information,financial information, and science & technology information.

As depicted in FIG. 8, the top news stories related to the user'sinterests are displayed in headline form. Furthermore, a multimediavideo clip stream related to the most important news story within theuser's interests is playing within a window of the web page display. Theuser can control the video clip using common VideoCassette Recorder(VCR) type controls such as play, stop, fast-forward, reverse, and mute.A video window as depicted in FIG. 8 may be implemented using aRealVideo viewer from RealNetworks of Seattle, Wash. or a NetShow viewerfrom Microsoft Corporation of Redmond, Wash. If the user is veryinterested in the story playing within the selected video clip, the usercan expand the video to fill the full screen of the client system. Theuser may also retrieve other information related to the displayed videoclip.

If the user is not interested in the video clip currently beingdisplayed, the user can select one of the other headlines to bring upinformation on that story. The information may consist of a video clip,an audio clip, a web page, a text story, or any other digitalinformation presentation.

The news web pages of the present invention can be created in typicalhierarchical organization that is familiar to most computer users. FIG.9 illustrates a conceptual diagram of a set of hierarchical web pagesthat have been created using the user's preferences and the availablemultimedia information. Thus, referring back to FIG. 8, if the user isnot interested in the video clip currently being displayed or any of thecurrent headlines, the user can select one of the different headlinecategories. The web server will then present a web page with specificcategory information.

In one embodiment, the user can select one of the headlines in a storyto bring up a web page with additional stories in that category anddetailed information about the selected story. For example, if the userselects the “NJ Devils trade Star Wing” headline the Sports news webpage illustrated in FIG. 10 may be presented. As illustrated in FIG. 10,a video clip of the hockey player trade is displayed. Furthermore, theweb page displays sports related news as a list of sports headlines. Inthe example of FIG. 10, the sports category sub-categories of NFLHeadlines, NBA headlines, NHL headlines, and Other Sports Headlines aredisplayed.

Searching

The multimedia receiver/server system 700 can be used to provide customweb pages created in response to a user's query. For example, FIG. 10illustrates a search term input box wherein a user may enter one or moresearch terms. More detailed searching can be performed by selecting the“search” prompt. As illustrated in FIG. 10, a user has requested asearch to be performed using the term “Geocast.” Referring back to FIG.7, the web page construction application 760 uses the entered searchterm to search the multimedia directory 755. Furthermore, the web pageconstruction application 760 may examine descriptor information formultimedia streams currently being received such that “live” content maybe incorporated.

Using the located information that is related to the search terms, theweb page construction application 760 dynamically creates a web pagethat may be presented to the user. FIG. 11 illustrates an example of aweb page that may be created after searching the multimedia directory755 with the search term “Geocast”. As illustrated in FIG. 11, thedynamically generated web page contains a list of headlines from storiesor multimedia streams related to the search term. The detailedinformation from most important story may be presented in a separatewindow as illustrated in FIG. 11. In this example, the multimediainformation is a short text story with an accompanying audio stream ofan official company announcement. Furthermore, the web page constructionapplication 760 may include information from stories or multimediainformation that may be related to the search terms.

In one embodiment wherein the multimedia receiver/server system 700 iscoupled to the Internet, the web page construction application 760 mayalso include information retrieved from the Internet. Thus, themultimedia receiver/server system 700 can be used to merge multimediainformation received over the data broadcast network with informationretrieved from the Internet into a single display.

A Data Broadcasting Service

As disclosed, the present invention teaches methods and apparatus forimplementing a broadband data broadcast system. The broadband databroadcast system allows rich multimedia information to be delivered toend-users that have narrowband or even no connection to the Internet.The broadband data broadcast system can be used to create a broadbanddata broadcast information service.

In one embodiment, the broadband data broadcast information serviceoperates by selling multimedia receiver/server devices to consumers thatdesire service. The consumers connect their multimedia receiver/serverdevices to appropriate client systems such as personal computers,television set-top boxes, and home networks.

In one embodiment, a stand-alone multimedia receiver/display device maybe sold such that users can use the service without having to have anyother client system. Such an embodiment would be similar to theembodiment of FIG. 5 except that the client interface circuitry 590would be replaced by a display device that is capable of displayinginformation and the software would include client software fordisplaying information on the display device.

The broadband data broadcast service could be subscription based,advertiser supported, or a combination of paid subscription content andadvertiser supported content. In a preferred embodiment, a significantamount of information is broadcast without a subscription requirementbut is accompanied by advertising multimedia information that isdisplayed concurrently or intermittently. For example, an advertisementwindow can be added to the screen displays of FIGS. 8, 10, and 11. Dueto the broadband nature of the disclosed data broadcasting system, theadvertisement window can include video and audio information. Thus, thebroadband data broadcast system of the present invention permitsadvertisers to provide a rich multimedia message to users.

The advertisements can be accompanied by additional detailed informationand programs stored locally on the file system 750. Thus, when a user isinterested in a particular advertisement, the user can obtain thatadditional information or run programs associated with theadvertisement. For example, an advertisement for a catalog basedclothing merchant can be linked to a full version of the merchant'sclothing catalog stored locally on the multimedia receiver/server device700. Advertisers that desire to have large commercial documents such asproduct catalogs stored within the cache of the multimediareceiver/server systems could be charged a fee for such a privilege. Thefee may be related to the amount of time that the commercial documentswill be cached in the multimedia receiver/server device 700.

The user can browse the locally stored clothing catalog and select itemsfor purchase. If the user has an Internet connection, the user can fillout an order form to order an item from the catalog. The broadband databroadcast capability of the present invention allows the catalog toinclude far more detailed information than normally presented on anInternet web page. Furthermore, the caching capability of the systemallows all the catalog information to be stored locally for immediateand instantaneous access. Thus, it can be seen that the data broadcastservice of the present invention provides the rich multimedia experienceof radio and television along with the interactive browsing features ofthe Internet.

As depicted in FIGS. 3 a and 3 b, not all users of the multimediareceiver/server system of the present invention will have an Internet“back channel.” Thus, a user without an Internet connection that browsesa product catalog contained within the multimedia receiver/server systemcannot initiate an Internet based ecommerce transaction. For such users,FIG. 5 illustrates one embodiment of the present invention that includeswireless network circuitry 543 for providing a wireless back channel.For example, a contract may be made with a cellular telephone providerto obtain access to the Short Messaging Service (SMS) portion of theircellular telephone network. The wireless network circuitry 543 mayprovide significant bandwidth to enable complex transactions such asonline gaming, however the wireless network circuitry 543 need onlyprovide a narrowband connection for ecommerce applications such aspurchase orders.

In addition to advertiser supported content, a number of subscriptionfee based premium services can be offered using the directed broadcastsystem of the present invention. For example, a special financialinformation subscription package may be offered that contains real-timestock quotes and in-depth financial news. Such subscription fee basedpremium data broadcast services would be protected by encrypting thedigital information streams containing the premium content. To preventpiracy, the encryption system can be aided with the use of tamper-proofencryption circuitry 545 as depicted in FIG. 5. The tamper-proofencryption circuitry 545 contains private keys that cannot be accessed.Attempts to access the secret encryption keys within the encryptioncircuitry 545 will destroy the encryption circuitry 545. In oneembodiment, the secure encryption module 870 comprises an iButton fromDallas Semiconductor of Dallas, Tex.

The foregoing has described a directed data broadcast system. It iscontemplated that changes and modifications may be made by one ofordinary skill in the art, to the materials and arrangements of elementsof the present invention without departing from the scope of theinvention.

We claim:
 1. A computer-implemented method comprising: receiving adigital broadcast signal including a transport stream comprising aplurality of elementary streams and a plurality of multimediadescriptors, each multimedia descriptor identifying characteristicsassociated with at least one of the plurality of multimedia streams, thecharacteristics including elementary stream identification and category,and each multimedia descriptor preceding the multimedia stream withwhich it is associated wherein each descriptor describes the elementarystream with which it is associated and comprises one or more key wordsembedded within the digital broadcast signal; identifying one or moreelementary streams associated with one or more multimedia descriptorsthat match a set of preprogrammed interest category parameters; cachingthe entirety of the one or more identified elementary streams responsiveto the one or more identified elementary streams matching the set ofpreprogrammed interest category parameters; and automatically generatinga customized information page operable to simultaneously include thepreprogrammed interest category parameters and a list comprising aplurality of cached elementary streams sorted based upon thepreprogrammed interest category parameters into which the plurality ofcached elementary streams belong, the cached elementary streams beingavailable for retrieval by a user and a selected cached elementarystream being operable to be displayed simultaneously with the list ofcached elementary streams sorted by preprogrammed interest categoryparameter.
 2. The method of claim 1, wherein receiving comprisesreceiving the digital broadcast signal from one or more terrestrialdigital television broadcast sources.
 3. The method of claim 1, whereinone or more elementary streams on the customized information page arerepresented as moving picture streams.
 4. The method of claim 1, furthercomprising using the multimedia descriptor to create a multimediadirectory that references the one or more cached elementary streams. 5.The method of claim 1, wherein the preprogrammed interest parameterscomprise at least one information category of interest to the user. 6.The method of claim 1, further comprising: retrieving supplementalinformation from the Internet that matches a set of preprogrammedinterest parameters; and incorporating the supplemental information intothe customized information page.
 7. The method of claim 1, furthercomprising: receiving a user query; identifying any live multimediastreams that satisfy the user query; identifying any previously-cachedelementary streams that satisfy the user query; and dynamicallygenerating a second customized information page including any identifiedlive and previously-cached elementary streams in response to the userquery.
 8. The method of claim 1, wherein the customized information pagecomprises a web page.
 9. A method for distributing data, comprising:multiplexing a plurality of multimedia streams received from a pluralityof data sources; modulating the multiplexed streams into a digitalsignal comprising a transport stream; broadcasting the modulated digitalsignal; a shared multimedia receiver receiving the broadcasted signal;the shared multimedia receiver demodulating the broadcasted signal; theshared multimedia receiver providing the demodulated broadcast signal toa first receiving system and a second receiving system over a local areanetwork; demultiplexing at least a portion of the plurality ofmultimedia streams to identify multimedia descriptor informationincluded in the broadcasted signal, the multimedia descriptorinformation comprising a category description; caching a firstdemultiplexed stream within the first receiving system, the firstdemultiplexed stream containing data within the multimedia descriptorinformation that match a first set of preprogrammed interest parameters;caching a second demultiplexed stream within the second receivingsystem, the second demultiplexed stream containing data within themultimedia descriptor information that match a second set ofpreprogrammed interest parameters; and automatically generating acustomized information page within each receiving system including onthe customized information page the one or more cached multimediastreams for retrieval by a user.
 10. The method of claim 9, whereinbroadcasting comprises broadcasting the modulated digital signal usingexcess broadcast capacity of a wireless terrestrial digital televisiontransmission system.
 11. The method of claim 9, wherein broadcastingcomprises broadcasting the modulated digital signal using excessbroadcast capacity of a plurality of wireless terrestrial digitaltelevision transmission systems.
 12. The method of claim 9, wherein theeach multimedia stream is associated with a multimedia descriptor, andwherein caching comprises caching a multimedia stream having anassociated multimedia descriptor that satisfies a particular set ofpreprogrammed interest parameters.
 13. A system comprising: a front-endreceiver to obtain a digital broadcast signal comprising a plurality ofmultimedia streams comprising a plurality of transport streams and aplurality of multimedia descriptors, each of the plurality of multimediadescriptors being associated with at least one of the plurality oftransport streams, and each of the plurality of multimedia descriptorspreceding the multimedia stream with which it is associated, whereineach descriptor describing the multimedia stream with which it isassociated comprises one or more key words embedded within the digitalbroadcast signal describing a category associated with content includedwithin an associated stream; a cache store operable to receive amultimedia stream identified as associated with one or more multimediadescriptors that match a set of preprogrammed interest parameters andoperable to cache the entirety of the identified multimedia stream; anda processor operable execute a page-building component to automaticallygenerate a customized information page including the cached multimediastream for retrieval by a user.
 14. The system of claim 13, wherein thefront-end receiver comprises at least one digital television receiver toobtain the digital broadcast signal from one or more terrestrial digitaltelevision broadcast sources.
 15. The system of claim 14, wherein thedigital broadcast signal comprises an MPEG-2 transport protocol streamreceived with an ATSC digital television signal.
 16. The system of claim13, wherein the front-end receiver comprises at least one of a satellitetelevision receiver and a cable television receiver.
 17. The system ofclaim 13, wherein the caching component is to use the multimediadescriptor to create a multimedia directory that references the cachedmultimedia stream.
 18. The system of claim 13, wherein the preprogrammedinterest parameters comprise at least one information category ofinterest to the user.
 19. The system of claim 13, wherein thepage-building component is to receive supplemental information from theInternet that matches a set of preprogrammed interest parameters andincorporate the supplemental information into the customized informationpage.
 20. The system of claim 13, wherein the page-building component isto receive a user query; wherein the caching component is to identifyany live or previously-cached multimedia streams that satisfy the userquery; and wherein the page-building component is further to dynamicallygenerate a second customized information page including any identifiedlive and previously-cached multimedia streams in response to the userquery.
 21. The system of claim 13, wherein the customized informationpage comprises a web page.
 22. A system comprising: a front-end receiverto obtain a digital broadcast signal comprising a plurality ofmultimedia streams; a caching component to identify, for each of aplurality of client systems, a multimedia stream that matches a set ofpreprogrammed interest parameters for a particular client system to oneor more multimedia descriptors embedded within the multimedia streamcomprising a category associated with content included in the multimediastream and to cache each identified multimedia stream and a livemultimedia stream that matches the set of preprogrammed interestparameters for a particular client system for a plurality of clientsystems, the caching component to compare the set of preprogrammedinterest parameters to the plurality of multimedia descriptors precedingthe multimedia stream, wherein the multimedia descriptors comprise oneor more key words embedded within the digital broadcast system; and apage-building component to automatically generate a first customizedinformation page for each client system comprising an identified cachedmultimedia stream and an identified live multimedia for retrieval by arespective user, and wherein the one or more identifiedpreviously-cached multimedia streams and one or more identified livemultimedia streams-are organized on the first customized informationpage by topic; wherein the page-building component is to receive a userquery from a particular client system; and wherein the caching componentis to identify any live or previously-cached multimedia streams thatsatisfy the user query; and wherein the page-building component isfurther to dynamically generate a second customized information pageincluding any live and previously cached multimedia streams in responseto the user query.
 23. The system of claim 22, wherein the front-endreceiver comprises a digital television receiver to obtain the digitalbroadcast signal from one or more terrestrial digital televisionbroadcast sources.
 24. The system of claim 23, wherein the digitalbroadcast signal comprises an MPEG-2 transport protocol stream receivedwith an ATSC digital television signal.
 25. The system of claim 22,wherein the front-end receiver comprises one of a satellite televisionreceiver and a cable television receiver.
 26. The system of claim 22,further comprising a rebroadcasting component to rebroadcast a cachedmultimedia stream to a client system.
 27. The system of claim 26,wherein the rebroadcasting component is to rebroadcast the cached mediastream over a local area network.
 28. The system of claim 22, whereineach identified multimedia stream is associated with a multimediadescriptor, and wherein the caching component is to compare a multimediadescriptor with the set of preprogrammed interest parameters for theparticular client system.
 29. The system of claim 28, further whereinthe caching component is to generate a multimedia directory thatreferences each cached multimedia stream using information from therespective multimedia descriptors.
 30. The system of claim 22, whereinthe preprogrammed interest parameters for each client system comprise atleast one information category of interest to an associated user. 31.The system of claim 22, wherein the page-building component is toretrieve supplemental information from the Internet that matches a setof preprogrammed interest parameters for a particular client system andincorporate the supplemental information into the customized informationpage for that client system.
 32. The method of claim 2, wherein thedigital broadcast signal comprises an MPEG-2 transport protocol streamreceived with an ATSC digital television signal.